Transit-Oriented Development (TOD) is an urban planning approach that encourages a modal shift from private to public transportation. This shift can generate additional benefits from a sustainability perspective. This study aims to assess the efficiency of TOD by applying the data envelopment analysis (DEA) method. The ridership of public transportation is considered as the direct output characteristic of TOD efficiency, and nine indicators of ridership are selected as inputs on the basis of the core concepts of TOD. These concepts include density, diversity, and design (3Ds).
The Tokyu Den-en Toshi Line in Japan is presented as a typical case of TOD because this line includes TOD and non-TOD stations. Assessing and comparing the results of all railway stations reveal that almost all indicator values of non-TOD stations are higher than those of TOD stations. The results suggest that TOD planning and programs are inefficient in terms of ridership generation. This implication, however, may be attributed to the inadequacy of the selected indicators for TOD assessment.
The results obtained after adding operation year as input indicators and removing transfer station show that TOD stations perform efficiently and in accordance with expectations. This response indicates that the inclusion of influential factors is necessary for equitable TOD assessment.
Therefore, other influential factors must be considered when evaluating the efficiency of TOD-based stations with different inherent attributes. In addition, the design input with the largest impact on all inefficient units was identified, suggesting that management of bus service and railway system should be well enhanced.
Transportation Infrastructure
Transportation infrastructure is one of the most important components of urban development. The efficient development and implementation of a transportation infrastructure plan are necessary to solve traffic congestion, greenhouse gas emissions, and other environmental consequences that accompany rapid urbanization and motorization. From the perspective of sustainable and integrated urban development, the imbalance between land use and transportation systems is the most critical factor that affects the efficiency of transportation infrastructure. Transit-Oriented Development (TOD) strategy has been proposed as an efficient approach to solve this imbalance.
TOD aims to encourage the use of public transportation by increasing population density and mixed land use in areas surrounding transportation hubs and by promoting connectivity between stations and trip origins/destinations. Although the formal term of TOD was not introduced until 1993, its underlying principle has been applied and implemented as a solution to urban growth challenges since the late 19th and early 20th centuries, mainly in the United States and Europe. Later, in 1997, the density, diversity, and design (3D) framework of TOD was proposed and explained. In several American cities, the 3D-based TOD plan has increased the ridership and modal shares of public transport and has decreased vehicle mileage by 3%–5%. Accordingly, the TOD concept has been applied with an emphasis on the 3D framework in urban and transport planning worldwide. However, its efficiency in practical applications may sometimes not meet expectations. The low utilization of public transport cannot achieve the sustainable cycle of land–people–transport [11]. In other words, whether or not the TOD strategy can play its due role in urban planning and management is inconclusive. Therefore, evaluating the efficiency of TOD is a necessary challenge faced by urban administrators and policy makers who aim to successfully implement, enhance, and improve TOD.
To respond to such a demand, this study selects the appropriate indicators that reflect the 3D concept of TOD in practice. This study assesses the efficiency of a railway system that was developed on the basis of the 3D framework of TOD. Furthermore, it provides advice to improve the factors that most significantly influence the efficiency of TOD. In this study, data envelopment analysis (DEA), which was first proposed by Charnes et al. in 1978, is applied. Since its introduction, DEA has been widely used to measure the relative efficiency of various organizations, referred to as decision-making units (DMU), with multiple inputs and outputs]. DEA can identify the input with the largest impact on an inefficient unit. Such input can provide guidelines to policy makers. One line of the Japanese railway system is presented as a case study. In Japan, the integration of the transport system and land use has been practiced since the 1910s. This practice is consistent with the concept of TOD. After more than a century, the country has recognized advancements in railway operation and management. The efficiency evaluation of TOD cases in Japan can provide essential guidance or experiences for future transport and urban planning in other countries, especially in developing countries experiencing rapid urbanization.
Literature Review
The integration of transportation and land use dates back to the post-World War II era, when planners in Europe, most notably in Stockholm and Copenhagen, led suburban development into satellite areas along transit corridors. Since the 1990s, a series of new concepts and approaches, such as the Smart Growth concept and New Urbanism approach, for the integration of transportation and land use have emerged to combat uncontrolled urban sprawl. TOD is also gaining popularity as an approach to promote smart growth and sustainable development in the metropolitan areas of many developed and developing countries where mass transit systems have been implemented to relieve traffic congestion.
A common definition or criterion remains to be established for TOD despite the substantial body of research that has discussed the concept. For example, Cervero et al. stressed the contributions of the 3Ds to the TOD concept; furthermore, they explained the 3D concept as density in the form of residence and jobs, diversity in the form of mixed land-use development, and design in the form of good street connectivity for pedestrians. Other scholars interpreted TOD by borrowing words from its original explanation and providing new empirical additions. The various definitions for TOD generally state that TOD should promote compact and highly mixed-use development around transit hubs and should include accessible and walkable neighborhoods.
Existing studies have demonstrated that TOD provides numerous advantages, such as facilitating polycentric cities and regions, mitigating urban sprawl, boosting public transport ridership, increasing bike usage and walkability, accommodating economic growth, and creating sustainable neighborhoods. The most important function of TOD is to reduce traffic congestion and increase public transit use in areas experiencing accelerated urban development. TOD has attracted increasing attention as a solution to the challenges of urban growth given its widely recognized benefits. TOD implementation, however, is not always successful. Thus, several studies have evaluated the efficiency of TOD (e.g.,). Most existing research applied single and several indicators to measure the outcomes or benefits that TOD provides in terms of travel behavior, economics, and environment. Ridership is one of most representative indicators of TOD outcome. Renne and Wells monitored the success of TOD through a survey that included and summarized the various indicators of the influences and the most useful indicators of TOD. However, this study quantified TOD in the form of a single indicator and provided a limited explanation for the ridership efficiency of TOD. In addition, it lost meaningful information for the aspects that contribute to the success or failure of TOD. The multi-indicator evaluation method involves weight setting for each indicator. However, weight setting in existing studies is often empirical or less objective and could provide biased results.
In the past decade, DEA has been widely used to measure the efficiency of different models of transportation system operations or management. The most significant advantage of DEA over traditional weight-based methods is that DEA does not require weight parameters to measure efficiency. Researchers have employed DEA to address two main research topics. One topic is the analysis and comparison of the efficiency of firms, networks, or nations in the field of economics and management science. Only a small part of related works has focused on the evaluation of the operational performance and management of railways. The other topic is the selection of the optimal solution for actual operations in vehicle dispatching and route planning. Up to now, DEA has not been applied in the assessment of transportation strategy, at least in terms of TOD.
Discussion and Conclusions
This study focused on measuring the efficiency of the TOD strategy implemented in the DT Line. TOD is a powerful urban planning approach and concept that is applied to resolve various urban problems. This study expounded on TOD assessment on the basis of the 3D framework. In this study, the assessment procedure included the identification of catchment areas and the selection of suitable indicators as input variables and ridership as output variables. The input variables are then subjected to the DEA method to validate the successful performance of the TOD strategy or program and to identify possible solutions to strengthen TOD implementation.
Existing TOD evaluations have failed to provide reliable conclusions regarding TOD performance. For example, a single-indicator assessment cannot adequately characterize the comprehensive efficiency level of a TOD strategy from the perspective of the 3D framework. Meanwhile, a simple weight-based method following the 3D concept is likely to be affected by weights with low objective values and may thus produce a biased result that may contradict reality. These situations suggest the necessity of designing a procedure for the comprehensive assessment of TOD strategies. By considering that density and diversity may generate transportation demand and that design must provide convenient service to satisfy such needs, we employed DEA to reflect the relative efficiency of TOD in accordance with 3D-based inputs and ridership output. Our DEA-derived results reflect the core principle of the TOD concept, which coordinates density, diversity, and design with ridership output.
Many TOD applications have demonstrated that TOD has a significant role in regional development. However, the present results suggested that TOD strategies cannot provide more positive effects than non-TOD strategies because, on the one hand, market power enables non-TOD strategies to achieve effects similar to those achieved by TOD strategies. More importantly, the current indicators selected for TOD assessment do not adequately reflect the 3D concept. In fact, the current indicators for TOD assessment only highlight aspects related to 3D, and some important factors that affect output are excluded from conventional TOD assessment. For example, operating history can also affect the output of TOD stations along the DT Line. Although TOD stations are comparable with non-TOD stations in general, development history results in the incomparable efficiency of new and old stations. Moreover, other factors, such as the age and social class of the catchment population, designation as transfer station, number of trains running per day, and duration between trips, have been overlooked. Adding operation year as an input indicator and removing transfer station revealed that the performance of TOD stations is relatively efficient and approaches expectations. This result indicated that the inclusion of other influential factors is necessary for equitable TOD assessment. Consequently, taking such factors into account is indispensable when evaluating the efficiency of TOD stations with different inherent attributes. In addition, the design input with the largest impact on all inefficient units was identified. Management of bus service and railway system should be well enhanced and encouragement for public transportation usage should be emphasized.
The applicability of the DEA-based TOD assessment approach is mainly dependent on indicator selection. The framework of the approach includes indicator selection from the perspective of 3Ds, catchment divisions, and the DEA model and is applicable to other public transportation systems (e.g., light rail, metro, bus, and bus rapid transit) and to other regions or countries. Nevertheless, the selected indicators may vary across different applications. Researchers and urban planners may have specific local or specialized priorities and knowledge that differ from those emphasized in the present case. Thus, other researchers should select indicators that are appropriate for their priorities and knowledge.
Nevertheless, the present study presents several critical issues that should be considered to improve the evaluation of TOD approaches. First, additional factors that affect the efficiency of TOD-based systems should be considered during the assessment and planning of a TOD project. These factors include the attributes of the target population (age structure, occupation, and income level) and the transportation system itself. Second, the design scheme should improve the convenience of accessing destinations by foot, bus, or bicycle. In this study, the selected indicators mainly characterized connectivity to railway stations by bus. However, such a characterization may be insufficient for design characterization. Other factors, such as plating strips, overhead lights, and bicycle path lengths, should be considered in future studies. Furthermore, the definition of the analytical unit is crucial for TOD assessment. In this study, the Nationwide Person Trip Survey in Japan was used to identify station catchment areas through the boundary method. When such data are unavailable, the effect of catchment size should be addressed by specifying a different buffer radius, travel distance, or travel time.
